Prolactin

prolactin

PDB rendering based on 1n9d.
Identifiers
Symbol PRL
External IDs OMIM: 176760 MGI: 97762 HomoloGene: 732 GeneCards: PRL Gene
Orthologs
Species Human Mouse
Entrez 5617 19109
Ensembl ENSG00000172179 ENSMUSG00000021342
UniProt P01236 P06879
RefSeq (mRNA) NM_001163558 NM_001163530
RefSeq (protein) NP_000939 NP_001157002
Location (UCSC) Chr 6:
22.4 – 22.41 Mb		 Chr 13:
27.15 – 27.16 Mb
PubMed search [3] [4]

Prolactin (PRL) also known as luteotropic hormone (LTH) is a protein that in humans is encoded by the PRL gene.[1]

Prolactin is a peptide hormone discovered by Henry Friesen. Although it is perhaps best known for its role in lactation, prolactin already existed in the oldest known vertebrates—fishes—where its most important functions were probably related to control of water and salt balance.

Prolactin also acts in a cytokine-like manner and as an important regulator of the immune system. Prolactin has important cell cycle related functions as a growth-, differentiating- and anti-apoptotic factor. As a growth factor binding to cytokine like receptors it has also profound influence on hematopoiesis, angiogenesis and is involved in the regulation of blood clotting through several pathways. In summary, "more than 300 separate actions of PRL have been reported in various vertebrates, including effects on water and salt balance, growth and development, endocrinology and metabolism, brain and behavior, reproduction, and immune regulation and protection". Prolactin acts in endocrine, autocrine, and paracrine manner through the prolactin receptor and a large number of cytokine receptors.[2]

Pituitary prolactin secretion is regulated by endocrine neurons in the hypothalamus, the most important ones being the neurosecretory tuberoinfundibulum (TIDA) neurons of the arcuate nucleus, which secrete dopamine to act on the dopamine-2 receptors of lactotrophs, causing inhibition of prolactin secretion. Thyrotropin-releasing factor (thyrotropin-releasing hormone) has a stimulatory effect on prolactin release.

Vasoactive intestinal peptide and peptide histidine isoleucine help to regulate prolactin secretion in humans, but the functions of these hormones in birds can be quite different.[3]

Prolactin is sometimes classified as a gonadotropin[4] although in humans it has only a weak luteotropic effect while the effect of suppressing classical gonadotropic hormones is more important.[5]

Contents

Effects

Prolactin has many effects including regulating lactation and stimulating proliferation of oligodendrocyte precursor cells.

It stimulates the mammary glands to produce milk (lactation): Increased serum concentrations of prolactin during pregnancy cause enlargement of the mammary glands of the breasts and prepare for the production of milk. However, the high levels of progesterone during pregnancy suppress the production of milk. Milk production normally starts when the levels of progesterone fall by the end of pregnancy and a suckling stimulus is present. Sometimes, newborn babies (males as well as females) secrete a milky substance from their nipples known as witch's milk. This is in part caused by maternal prolactin and other hormones.

Prolactin provides the body with sexual gratification after sexual acts: The hormone counteracts the effect of dopamine, which is responsible for sexual arousal. This is thought to cause the sexual refractory period.[6] The amount of prolactin can be an indicator for the amount of sexual satisfaction and relaxation. Unusually high amounts are suspected to be responsible for impotence and loss of libido (see hyperprolactinemia symptoms).

Prolactin also stimulates proliferation of oligodendrocyte precursor cells. These cells differentiate into oligodendrocytes, the cells responsible for the formation of myelin coatings on axons in the central nervous system.[7]

Prolactin also has a number of other effects including contributing to surfactant synthesis of the fetal lungs at the end of the pregnancy and immune tolerance of the fetus by the maternal organism during pregnancy; it also decreases normal levels of sex hormones — estrogen in women and testosterone in men.[8] It is this inhibition of sex steroids that is responsible for loss of the menstrual cycle in lactating women as well as lactation-associated osteoporosis. Prolactin also enhances luteinizing hormone-receptors in Leydig cells, resulting in testosterone secretion, which leads to spermatogenesis. Prolactin delays hair regrowth in mice.[9]

It has been shown that Prolactin promotes neurogenesis.

Production and regulation

In humans, prolactin is produced at least in the pituitary, decidua, myometrium, breast, lymphocytes, leukocytes and prostate.[10][11]

Pituitary PRL is controlled by the Pit-1 transcription factor and ultimately dopamine, extrapituitary PRL is controlled by a superdistal promoter and apparently unaffected by dopamine.[11]

In decidual cells and in lymphocytes the distal promoter and thus prolactin expression is stimulated by cAMP. Responsivness to cAMP is mediated by an imperfect cAMP–responsive element and two CAAT/enhancer binding proteins (C/EBP).[11] Progesterone has been observed to upregulate prolactin synthesis in the endometrium but decreases it myometrium and breast glandular tissue.[12] However breast and other tissues may also express the Pit-1 promoter in addition to the distal promoter.

Extrapituitary production of prolactin is thought to be special to humans and primates and may serve mostly tissue specific paracrine and autocrine purposes. It has been hypothesized that in other vetrabrates such as mice a similar tissue specific effect is achieved by a large family of prolactin like proteins controlled by at least 26 paralogous PRL genes not present in primates.[11]

Variance in levels

There is a diurnal as well as an ovulatory cycle in prolactin secretion. In many mammals, there is also a seasonal change in prolactin release.

During pregnancy, high circulating concentrations of estrogen and progesterone inhibit the action of prolactin on milk production. Following delivery, reduced estrogen and progesterone production allows prolactin to induce lactation.

After childbirth, prolactin levels fall as the internal stimulus for them is removed. Sucking by the baby on the nipple then promotes further prolactin release, maintaining the ability to lactate. The sucking activates mechanoreceptors in and around the nipple. These signals are carried by nerve fibers through the spinal cord to the hypothalamus, where changes in the electrical activity of neurons that regulate the pituitary gland cause increased prolactin secretion. The suckling stimulus also triggers the release of oxytocin from the posterior pituitary gland, which triggers milk let-down: Prolactin controls milk production (lactogenesis) but not the milk-ejection reflex; the rise in prolactin fills the breast with milk in preparation for the next feed.

In usual circumstances, in the absence of galactorrhea, lactation will cease within one or two weeks of the end of demand breastfeeding.

It has also been found that compared to un-mated males, fathers and expectant fathers have increased prolactin concentrations.[13]

High prolactin levels also tend to suppress the ovulatory cycle by inhibiting the secretion of both follicle-stimulating hormone (FSH) and gonadotropic-releasing hormone (GnRH). High prolactin levels can also contribute to mental health issues.

Prolactin levels peak during REM sleep, and in the early morning. Levels can rise after exercise, meals, sexual intercourse, minor surgical procedures,[14] or following epileptic seizures.[15]

Hypersecretion of prolactin is more common than hyposecretion. Hyperprolactinemia is the most frequent abnormality of the anterior pituitary tumors. Clinical signs include inappropriate lactation, lack of menses, infertility in females, and impotence in males.

Structure

The structure of prolactin is similar to that of growth hormone and placental lactogen. The molecule is folded due to the activity of three disulfide bonds. Significant heterogeneity of the molecule has been described, thus bioassays and immunoassays can give different results due to differing glycosylation, phosphorylation, sulfation, as well as degradation. The non-glycosylated form of prolactin is the dominant form of prolactin that is secreted by the pituitary gland.

There are mainly three different forms of prolactin in regard to size:

The levels of larger ones are somewhat higher during the early postpartum period.[19]

Pit-1 is a transcription factor that binds to the prolactin gene at several sites to allow for the production of prolactin in the pituitary gland. A key regulator of prolactin production is estrogens that enhance growth of prolactin-producing cells and stimulate prolactin production directly, as well as suppressing dopamine.

Human prolactin receptors are insensitive to mouse prolactin.[20]

Prolactin receptor

Main article: Prolactin receptor

Prolactin receptors are present in the mamillary glands, ovaries, pituitary glands, heart, lung, thymus, spleen, liver, pancreas, kidney, adrenal gland, uterus, skeletal muscle, skin, and areas of the central nervous system.[21] When prolactin binds to the receptor, it causes it to dimerize with another prolactin receptor. This results in the activation of Janus kinase 2, a tyrosine kinase that initiates the JAK-STAT pathway. The activation of the prolactin receptor also results in the activation of mitogen-activated protein kinases and Src kinase.[21]

Diagnostic use

Prolactin levels may be checked as part of a sex hormone workup, as elevated prolactin secretion can suppress the secretion of FSH and GnRH, leading to hypogonadism, and sometimes causing erectile dysfunction in men.

Prolactin levels may be of some use in distinguishing epileptic seizures from psychogenic non-epileptic seizures. The serum prolactin level usually rises following an epileptic seizure.[22]

Units and unit conversions

The serum concentration of prolactin can be given in mass concentration (µg/L or ng/mL), molar concentration (nmol/L or pmol/L) or in international units (typically mIU/L). The current IU is calibrated against the third International Standard for Prolactin, IS 84/500.[23][24] Reference ampoules of IS 84/500 contain 2.5 µg of lyophilized human prolactin,[25] and have been assigned an activity of .053 International Units of prolactin.[23][24] Measurements that are calibrated against the current international standard can be converted into mass units using this ratio of grams to IUs;[26] prolactin concentrations expressed in mIU/L can be converted to µg/L by dividing by 21.2. Previous standards use other ratios.[27][28][29][30]

The first International Reference Preparation (or IRP) of human Prolactin for Immunoassay was established in 1978 (75/504 1st IRP for human Prolactin) at a time when purified human prolactin was in short supply.[26][27] Previous standards relied on prolactin from animal sources.[30] Purified human prolactin was scarce, heterogeneous, unstable, and difficult to characterize. A preparation labelled 81/541 was distributed by the WHO Expert Committee on Biological Standardization without official status and given the assigned value of 50 mIU/ampoule based on an earlier collaborative study.[26][28] It was determined that this preparation behaved anomalously in certain immunoassays and was not suitable as an IS.[26] However, in the absence of an alternative, it was used. Three different human pituitary extracts containing prolactin were subsequently obtained as candidates for an IS. These were distributed into ampoules coded 83/562, 83/573, and 84/500.[23][24][26][29] On the basis of collaborative studies involving 20 different laboratories, it was concluded that there was little difference between these three preparations. 83/562 appeared to be the most stable. This preparation was largely free of dimers and polymers of prolactin. On the basis of these investigations 83/562 was established as the Second IS for human Prolactin.[29] Once stocks of these ampoules were depleted, 84/500 was established as the Third IS for human Prolactin.[23][26]

Reference ranges

General guidelines for diagnosing prolactin excess (hyperprolactinemia) define the upper threshold of normal prolactin at 25 µg/L for women, and 20 µg/L for men.[21] Similarly, guidelines for diagnosing prolactin deficiency (hypoprolactinemia) are defined as prolatin levels below 3 µg/L in women,[31][32] and 5 µg/L in men.[33][34][35] However, different assays and methods for measuring prolactin are employed by different laboratories, and as such the serum reference range for prolactin is often determined by the laboratory performing the measurement.[21][36] Furthermore, prolactin levels also vary with, for example, age,[37] sex,[37] menstrual cycle stage,[37] and pregnancy.[37] The circumstances surrounding a given prolactin measurement (assay, patient condition, etc.) must therefore be considered before the measurement can be accurately interpreted.[21]

The following chart illustrates the variations seen in normal prolactin measurements across different populations. Prolactin values were obtained from specific control groups of varying sizes using the IMMULITE assay.[37]

Typical prolactin values
Proband Prolactin, µg/L
women, follicular phase (n = 803)
12.1
women, luteal phase (n = 699)
13.9
women, mid-cycle (n = 53)
17
women, whole cycle (n = 1555)
13.0
women, pregnant, 1st trimester (n = 39)
16
women, pregnant, 2nd trimester (n = 52)
49
women, pregnant, 3rd trimester (n = 54)
113
Men, 21–30 (n = 50)
9.2
Men, 31–40 (n = 50)
7.1
Men, 41–50 (n = 50)
7.0
Men, 51–60 (n = 50)
6.2
Men, 61–70 (n = 50)
6.9

Inter-method variability

The following table illustrates variability in reference ranges of prolactin between some commonly used assay methods, using a control group of healthy health care professionals (53 males, age 20–64 years, median 28 years; 97 females, age 19–59 years, median 29 years) in Essex, England:[36]

Assay method Mean
Prolactin		 Lower limit
2.5th percentile		 Upper limit
97.5th percentile
µg/L mIU/L µg/L mIU/L µg/L mIU/L
Females
Centaur 7.92 168 3.35 71 16.4 348
Immulite 9.25 196 3.54 75 18.7 396
Access 9.06 192 3.63 77 19.3 408
AIA 9.52[38] 257[38] 3.89[38] 105[38] 20.3[38] 548[38]
Elecsys 10.5 222 4.15 88 23.2 492
Architect 10.6 225 4.62 98 21.1 447
Males
Access 6.89 146 2.74 58 13.1 277
Centaur 7.88 167 2.97 63 12.4 262
Immulite 7.45 158 3.30 70 13.3 281
AIA 7.81[38] 211[38] 3.30[38] 89[38] 13.5[38] 365[38]
Elecsys 8.49 180 3.40 72 15.6 331
Architect 8.87 188 4.01 85 14.6 310

An example usage of table above is, if using the Centaur assay to estimate prolactin values in µg/L for females, the mean is 7.92 µg/L, and the reference range is 3.35–16.4 µg/L.

Conditions associated with elevated prolactin secretion

Hyperprolactinaemia, or excess serum prolactin, is associated with hypoestrogenism, anovulatory infertility, oligomenorrhoea, amenorrhoea, unexpected lactation, and loss of libido in women, and erectile dysfunction and loss of libido in men.

Hyperprolactinemia can result from:

Conditions associated with decreased prolactin

Hypoprolactinemia, or serum prolactin deficiency, is associated with ovarian dysfunction in women,[31][32] and metabolic syndrome, anxiety, arteriogenic erectile dysfunction, premature ejaculation,[33] oligozoospermia, asthenospermia, hypofunction of seminal vesicles, and hypoandrogenism[34] in men. In one study, normal sperm characteristics were restored when prolactin levels were brought up to normal values in hypoprolactinemic men.[35]

Hypoprolactinemia can result from:

See also

References

  1. ^ Evans AM, Petersen JW, Sekhon GS, DeMars R (May 1989). "Mapping of prolactin and tumor necrosis factor-beta genes on human chromosome 6p using lymphoblastoid cell deletion mutants". Somat. Cell Mol. Genet. 15 (3): 203–13. doi:10.1007/BF01534871. PMID 2567059. 
  2. ^ Bole-Feysot, C.; Goffin, V.; Edery, M.; Binart, N.; Kelly, P. A. (1998). "Prolactin (PRL) and its receptor: Actions, signal transduction pathways and phenotypes observed in PRL receptor knockout mice". Endocrine reviews 19 (3): 225–268. doi:10.1210/er.19.3.225. PMID 9626554.  edit
  3. ^ Kulick R, Chaiseha Y, Kang S, Rozenboim I, El Halawani M (2005). "The relative importance of vasoactive intestinal peptide and peptide histidine isoleucine as physiological regulators of prolactin in the domestic turkey". Gen Comp Endocrinol 142 (3): 267–73. doi:10.1016/j.ygcen.2004.12.024. PMID 15935152. 
  4. ^ Marieb, E.N. and Hoehn, K. (2006). Human Physiology & Anatomy. 7th ed. London: Benjamin Cummings. p605
  5. ^ MESH entry on Gonadotropins
  6. ^ New Scientist article on prolactin function relating to sex—University of Paisley and the ETH Zürich
  7. ^ Gregg C, Shikar V, Larsen P, et al. (2007). "White matter plasticity and enhanced remyelination in the maternal CNS". J. Neurosci. 27 (8): 1812–23. doi:10.1523/JNEUROSCI.4441-06.2007. PMID 17314279. 
  8. ^ Prolactinoma—Mayo Clinic
  9. ^ Craven AJ, Nixon AJ, Ashby MG, et al. (November 2006). "Prolactin delays hair regrowth in mice". J. Endocrinol. 191 (2): 415–25. doi:10.1677/joe.1.06685. PMID 17088411. http://joe.endocrinology-journals.org/cgi/content/abstract/191/2/415. 
  10. ^ Ben-Jonathan, N.; Mershon, J. L.; Allen, D. L.; Steinmetz, R. W. (1996). "Extrapituitary prolactin: Distribution, regulation, functions, and clinical aspects". Endocrine reviews 17 (6): 639–669. PMID 8969972.  edit
  11. ^ a b c d Gerlo, S.; Davis, J. R. E.; Mager, D. L.; Kooijman, R. (2006). "Prolactin in man: A tale of two promoters". BioEssays 28 (10): 1051–1055. doi:10.1002/bies.20468. PMC 1891148. PMID 16998840. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1891148.  edit
  12. ^ Zinger, M.; McFarland, M.; Ben-Jonathan, N. (2003). "Prolactin expression and secretion by human breast glandular and adipose tissue explants". The Journal of clinical endocrinology and metabolism 88 (2): 689–696. PMID 12574200.  edit
  13. ^ Nelson, R.J. (2005). An introduction to behavioral endocrinology (3rd ed.)/ Sunderland, MA: Sinauer Associates.
  14. ^ Melmed S, Jameson JL (2005). "333 Disorders of the Anterior Pituitary and Hypothalamus". In Jameson JN, Kasper DL, Harrison TR, Braunwald E, Fauci AS, Hauser SL, Longo DL.. Harrison's principles of internal medicine (16th ed.). New York: McGraw-Hill Medical Publishing Division. ISBN 0-07-140235-7. http://highered.mcgraw-hill.com/sites/0071402357/information_center_view0/. 
  15. ^ Mellors JDC (2005). "The approach to patients with "non-epileptic seizures"". Postgrad Med J. 81 (958): 498–504. doi:10.1136/pgmj.2004.029785. PMC 1743326. PMID 16085740. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1743326. 
  16. ^ a b c d [1] Sabharwal, P.; Glaser, R.; Lafuse, W.; Varma, S.; Liu, Q.; Arkins, S.; Kooijman, R.; Kutz, L. et al. (1992). "Prolactin synthesized and secreted by human peripheral blood mononuclear cells: an autocrine growth factor for lymphoproliferation". Proceedings of the National Academy of Sciences of the United States of America 89 (16): 7713–7716. Bibcode 1992PNAS...89.7713S. doi:10.1073/pnas.89.16.7713. PMC 49781. PMID 1502189. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=49781.  edit In turn citing:
    • Kiefer, K. A. & Malarkey, W. B. (1978) J. Clin. Endocrinol.
    Metab. 46, 119–124.
  17. ^ Garnier, P. E.; Aubert, M. L.; Kaplan, S. L.; Grumbach, M. M. (1978). "Heterogeneity of Pituitary and Plasma Prolactin in Man: Decreased Affinity of "Big" Prolactin in a Radioreceptor Assay and Evidence for Its Secretion". Journal of Clinical Endocrinology & Metabolism 47 (6): 1273–1281. doi:10.1210/jcem-47-6-1273.  edit
  18. ^ Lelte, Valerlano; Cosby, Helle; Sobrinho, Luis G.; Fresnoza, Agnes; Santos, M. Amparo; Frlesen, Henry G. (1992). "Characterization of big, big prolactin in patients with hyperprolactinaemia". Clinical Endocrinology 37 (4): 365–372. doi:10.1111/j.1365-2265.1992.tb02340.x. PMID 1483294.  edit
  19. ^ Kamel, MA; Neulen, J; Sayed, GH; Salem, HT; Breckwoldt, M (1993). "Heterogeneity of human prolactin levels in serum during the early postpartum period". Gynecological endocrinology : the official journal of the International Society of Gynecological Endocrinology 7 (3): 173–7. PMID 8291454.  edit [2]
  20. ^ Utama FE, LeBaron MJ, Neilson LM, et al. (2006). "Human prolactin receptors are insensitive to mouse prolactin: implications for xenotransplant modeling of human breast cancer in mice". J. Endocrinol. 188 (3): 589–601. doi:10.1677/joe.1.06560. PMID 16522738. http://joe.endocrinology-journals.org/cgi/content/abstract/188/3/589. 
  21. ^ a b c d e Mancini, T.; Casanueva, FF; Giustina, A (2008). "Hyperprolactinemia and Prolactinomas". Endocrinology & Metabolism Clinics of North America 37 (1): 67. doi:10.1016/j.ecl.2007.10.013. PMID 18226731. 
  22. ^ Banerjee S, Paul P, Talib V (2004). "Serum prolactin in seizure disorders". Indian Pediatr 41 (8): 827–31. PMID 15347871. 
  23. ^ a b c d Schulster D, Gaines Das RE, Jeffcoate SL. (Apr 1989). "International Standards for human prolactin: calibration by international collaborative study.". J Endocrinol. 121 (1): 157–66. doi:10.1677/joe.0.1210157. PMID 2715755. 
  24. ^ a b c "WHO Expert Committee on Biological Standardization". Thirty-ninth Report, WHO Technical Report Series. World Health Organization. 1989. http://whqlibdoc.who.int/trs/WHO_TRS_786.pdf. Retrieved 2009-06-03. "86.1520, WHO/BS documents: 86.1520 Add 1, 88.1596" 
  25. ^ "WHO International Standard, Prolactin, Human. NIBSC code: 84/500, Instructions for use". WHO International Standard, Prolactin, Human. NIBSC code: 84/500, Instructions for use. NIBSC / Health Protection Agency. 1989. http://www.nibsc.ac.uk/documents/ifu/84-500.pdf. Retrieved 2011-03-21. 
  26. ^ a b c d e f Canadian Society of Clinical Chemists (Dec 1992). "Canadian Society of Clinical Chemists position paper: standardization of selected polypeptide hormone measurements". Clin Biochem. 25 (6): 415–24. doi:10.1016/0009-9120(92)90030-V. PMID 1477965. 
  27. ^ a b Gaines Das RE, Cotes PM. (Jan 1979). "International Reference Preparation of human prolactin for immunoassay: definition of the International Unit, report of a collaborative study and comparison of estimates of human prolactin made in various laboratories". J Endocrinol. 80 (1): 157–68. doi:10.1677/joe.0.0800157. PMID 429949. 
  28. ^ a b "WHO Expert Committee on Biological Standardization". Thirty-fifth Report, WHO Technical Report Series. World Health Organization. 1985. http://whqlibdoc.who.int/trs/WHO_TRS_725.pdf. Retrieved 2011-03-21. 
  29. ^ a b c "WHO Expert Committee on Biological Standardization". Thirty-seventh Report, WHO Technical Report Series. World Health Organization. 1987. http://whqlibdoc.who.int/trs/WHO_TRS_760.pdf. Retrieved 2011-03-21. 
  30. ^ a b Bangham DR, Mussett MV, Stack-Dunne MP (1963). "The second International Standard for Prolactin". Bull World Health Organ. 29: 721–8. PMC 2555104. PMID 14107744. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2555104. 
  31. ^ a b Kauppila A, Martikainen H, Puistola U, Reinilä M, Rönnberg L (Mar 1988). "Hypoprolactinemia and ovarian function". Fertil Steril. 49 (3): 437–41. PMID 3342895. 
  32. ^ a b Schwärzler P, Untergasser G, Hermann M, Dirnhofer S, Abendstein B, Berger P (Oct 1997). "Prolactin gene expression and prolactin protein in premenopausal and postmenopausal human ovaries". Fertil Steril. 68 (4): 696–701. doi:10.1016/S0015-0282(97)00320-8. PMID 9341613. 
  33. ^ a b Corona G, Mannucci E, Jannini EA, Lotti F, Ricca V, Monami M, Boddi V, Bandini E, Balercia G, Forti G, Maggi M (May 2009). "Hypoprolactinemia: a new clinical syndrome in patients with sexual dysfunction". J Sex Med. 6 (5): 1457–66. doi:10.1111/j.1743-6109.2008.01206.x. PMID 19210705. 
  34. ^ a b Gonzales GF, Velasquez G, Garcia-Hjarles M (1989). "Hypoprolactinemia as related to seminal quality and serum testosterone". Arch Androl. 23 (3): 259–65. doi:10.3109/01485018908986849. PMID 2619414. 
  35. ^ a b Ufearo CS, Orisakwe OE (September 1995). "Restoration of normal sperm characteristics in hypoprolactinemic infertile men treated with metoclopramide and exogenous human prolactin". Clin Pharmacol Ther. 58 (3): 354–9. doi:10.1016/0009-9236(95)90253-8. PMID 7554710. 
  36. ^ a b Table 2 in Beltran, L; Fahie-Wilson, MN; McKenna, TJ; Kavanagh, L; Smith, TP (2008 Oct). "Serum total prolactin and monomeric prolactin reference intervals determined by precipitation with polyethylene glycol: evaluation and validation on common immunoassay platforms". Clinical Chemistry 54 (10): 1673–81. doi:10.1373/clinchem.2008.105312. PMID 18719199.  edit
  37. ^ a b c d e Prolaktin at medical.siemens.com—reference ranges as determined from the IMMULITE assay method
  38. ^ a b c d e f g h i j k l The AIA essay values are also from Table 2 in Brendan 2008, like the other values, but it uses a different conversion factor of 27.0 mIU/L per µg/L, taken from the second international standard, IS 83/562).

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